Detecting beat information using a diverse set of correlations

Abstract

A beat analysis module is described for determining beat information associated with an audio item. The beat analysis module uses an Expectation-Maximization (EM) approach to determine an average beat period, where correlation is performed over diverse representations of the audio item. The beat analysis module can determine the beat information in a relative short period of time. As such, the beat analysis module can perform its analysis together with another application task (such as a game application task) without disrupting the real time performance of that application task. In one application, a user may select his or her own audio items to be used in conjunction with the application task.

1 . A beat analysis module for analyzing an audio item, comprising:
 an average beat period determination module for determining an average beat period of an audio item, the average beat period determination module being configured to use an Expectation-Maximization (EM) approach to determine the average beat period, wherein correlation is performed over plural representations of the audio item; and   a beat onset determination module for determining, on a basis of the average beat period, onset information associated within the commencement of beats within the audio item.   
     
     
         2 . The beat analysis module of  claim 1 , wherein the beat analysis module is used within an application module, wherein the beat analysis module is configured to determine the average beat period and the onset information substantially concurrently with respect to another task performed by the application module. 
     
     
         3 . The beat analysis module of  claim 2 , wherein the application module is a game module, wherein the beat analysis module is configured to determine the average beat period and the onset information substantially concurrently with respect to a game playing operation performed by the game module. 
     
     
         4 - 20 . (canceled) 
     
     
         21 . The beat analysis module of  claim 1 , wherein the correlation is performed over a first domain associated with a Fourier transform of an audio signal of the audio item. 
     
     
         22 . The beat analysis module of  claim 21 , wherein the correlation is performed over the first domain and a second domain associated with an inverse Fourier transform of the audio signal. 
     
     
         23 . The beat analysis module of  claim 22 , wherein the correlation is performed over the first domain, the second domain, and a third domain associated with a square of the audio signal. 
     
     
         24 . The beat analysis module of  claim 1 , wherein the onset information identifies an average beat onset for the audio item. 
     
     
         25 . The beat analysis module of  claim 24 , wherein the onset information identifies actual beat onsets for individual beats in the audio item. 
     
     
         26 . A method performed by a computing device, the method comprising:
 obtaining an audio signal of an audio item; and   using an Expectation-Maximization (EM) approach to determine an average beat period of the audio item by performing correlation over plural representations of the audio item.   
     
     
         27 . The method of  claim 26 , wherein using the EM approach comprises iteratively processing different representations of the audio signal until convergence. 
     
     
         28 . The method of  claim 26 , further comprising:
 determine a Fourier transform of sequences of samples of the audio signal;   constructing a vector that contains average frequency spectrum energy of the sequences of samples; and   performing Expectation-Maximization (EM) iterative procedure on the average frequency spectrum energy of the sequences of samples to determine the average beat period of the audio item.   
     
     
         29 . The method of  claim 28 , further comprising representing the sequences of samples as rows of a matrix. 
     
     
         30 . The method of  claim 26 , wherein using the EM approach comprises defining a prior beat period distribution as a flat distribution. 
     
     
         31 . The method of  claim 30 , wherein using the EM approach comprises using sufficient statistics corresponding to a beat period posterior distribution that is conditioned on the audio signal. 
     
     
         32 . A computer readable storage device storing computer readable instructions which, when executed by one or more processing devices, cause the one or more processing devices to perform acts comprising:
 obtaining an audio signal of an audio item; and   determining an average beat period of the audio item by performing correlation over plural representations of the audio item, the plural representations including at least a first representation of the audio signal after application of a transformation to the audio signal and a second representation after application of an inverse of the transformation to the audio signal.   
     
     
         33 . The computer readable storage device of  claim 32 , wherein the transformation is a Fourier transform and the inverse of the transformation is an inverse Fourier transform. 
     
     
         34 . The computer readable storage device of  claim 32 , the acts further comprising:
 performing an application task based on the average beat period.   
     
     
         35 . The computer readable storage device of  claim 34 , wherein the application task comprises governing an audio tempo based on the average beat period. 
     
     
         36 . The computer readable storage device of  claim 34 , wherein the application task comprises making an audio selection based on the average beat period. 
     
     
         37 . The computer readable storage device of  claim 32 , wherein the first representation is a frequency domain representation.